Litmus

Litmus is an email marketing optimization platform that enables marketers to build, test, and analyze email campaigns before deployment. The platform provides email previews across dozens of email clients and devices, showing how designs render in Outlook, Gmail, Apple Mail, and other common environments. It includes a drag-and-drop email builder along with spam testing, proofing, and approval workflows to help teams catch rendering issues and errors prior to sending. Analytics capabilities track email performance metrics such as opens, clicks, and engagement across different clients and geographies. The tool is used by email marketing teams, agencies, and enterprises that need to ensure consistent brand presentation and deliverability across the fragmented email client landscape.